Limitations of the lipid state hypothesis for atherosclerosis are revealed by X-ray diffraction measurements

Survival in patients with surgically treated brain metastases: does infratentorial location matter?

Surgical resection is a common treatment modality for brain metastasis (BM). Location of the BM might significantly impact patient survival and therefore might be considered in clinical decision making and patient counseling. In the present study, the authors analyzed infra- and supratentorial BM location for a potential prognostic difference. Between 2013 and 2019, 245 patients with solitary BM received BM resection at the authors' neuro-oncological center. In order to produce a covariate balance for commonly-known prognostic variables (tumor entity, age, preoperative Karnofsky Performance Score, and preoperative Charlson Comorbidity Index), a propensity score matching at a ratio of 1:1 between the cohort of patients with infra- and supratentorial BM location was performed using R. Overall survival (OS) rates were assessed for both matched cohorts of patients with BM. Sixty-one of 245 patients (25%) with solitary BM exhibited an infratentorial tumor location; 184 patients (75%) suffered from supratentorial solitary BM. Patients with infratentorial BM revealed a median OS of 11 months (95% confidence interval (CI) 7.4-14.6 months). Compared with this, median OS for the group of 61 individually matched patients with solitary supratentorial solitary BM was 13 months (95% CI 10.9-15.1 months) (p = 0.32). The present study suggests that the prognostic value of infra- and supratentorial BMs does not significantly differ in patients that undergo surgery for solitary BM. These results might encourage physicians to induce surgical therapy of supra- and infratentorial BM in a similar manner.

Thermal, dynamic mechanical, and dielectric analyses of some polyurethane biocomposites

Polymer biocomposites based on segmented poly(ester urethane) and extracellular matrix components have been prepared for the development of tissue engineering applications with improved biological characteristics of the materials in contact with blood and tissues for long periods. Thermal, dynamical, and dielectrical analyses were employed to study the molecular dynamics of these materials and the influence of changing the physical network morphology and hydrogen bond interactions accompanied by phase transitions, interfacial effects, and polarization or conductivity. All phenomena that concur in the tested materials are evaluated by cross-examination of the dynamic mechanical characteristic properties (storage modulus, loss modulus, and loss factor) and dielectric properties (relative permittivity, relative loss factor, and loss tangent) as a function of temperature. Comparative aspects were elucidated by calculating the apparent activation energies of multiplex experiments.

Phase behavior and crystalline structures of cholesteryl ester mixtures: a C-13 MASNMR study

Cholesteryl esters are a transport and storage form of cholesterol in normal physiology but also a significant lipid in atherosclerotic plaques. To understand better the molecular properties of cholesteryl esters in tissues and plaques, we have studied the polymorphic and mesomorphic features of pure and mixed cholesteryl esters by solid state C-13 NMR with magic angle sample spinning (MASNMR). The temperature-dependent properties of two single components (cholesteryl linoleate (CL, C18:2) and cholesteryl linolenate (CLL, C18:3)), four binary systems (cholesteryl palmitate (CP, C16:0) with CL, CLL or cholesteryl oleate (CO, C18:1), and CO/CL), one ternary system (CO/CP/CL), and one quaternary system (CO/CP/CL/CLL) were studied. The mixing ratios were based on the composition of an atherosclerosis plaque dissected from a cholesterol-fed New Zealand white rabbit. C-13 MASNMR determined the phase transition temperatures, identified the phases present in all systems, and provided novel information about molecular structures. For example, solid CL exhibited a disordered structure with multiple molecular conformations, whereas pure CLL had a crystalline structure different from the three most commonly characterized forms (MLII, MLI, BL). In binary mixtures, the crystalline structure of each cholesteryl ester species was identified by its own characteristic resonances. It was found that CP always existed in its native BL form, but CL and CO were influenced by the composition of the mixture. CL was induced to form MLII crystals by the coexisting CP (55 wt%). When CO was cooled from the isotropic phase, it existed as a mixture of MLII and an amorphous form. The presence of CP significantly accelerated the conversion of the amorphous form to the MLII form. For the ternary mixture co-dried from chloroform, CL cocrystallized with CO in the MLII form and CP existed in BL form. Addition of a small amount of CLL slightly increased the heterogeneity of the solid mixture, but had little effect on the crystal structures or the phase transitions. C-13 MASNMR represents a powerful method for physical characterization of cholesteryl ester mixtures reflecting the composition of biological samples.